Automatic stop for elevators



' (No Model.)

R. T. WITHERYS 85 B. E. BLAOKMAN.

AUTOMATIC STOP FOR ELEVATORS.

No. 595,507. Patented D55. 14.1897.

0.. I ll a 5m 0 2 I w w UNITED STATES PATENT FFICE.

ROBERT T. WITHERS AND BENJAMIN E. BLACKMAN, OF NEWV CASTLE, PENNSYLVANIA.

AUTOMATIC STOP FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 595,507, dated December 14, 1897. Application filed January 22, 1897. Serial No. 620,232. (No model.)

T0 at whom it may concern.-

Be it known that we, ROBERT T. WITHERS and BENJAMIN E. BLAOKMAN, citizens of the United States, residing at New Castle, in the county of Lawrence and State of Pennsylvania, have invented certain new and useful Improvements in Automatic Stops for Elevators, of which the following is a specification.

Our invention relates to elevators provided with cars or cages and means for raising and lowering them within a shaft, and more particularly to automatic safety devices for stopping the cage or car in case the lifting mechanism should break or fail to sustain the cage or car or the cable or cables supporting the car or cage should break or part, and has for its object to provide means for automatically arresting and stopping the fall of the cage or car.

We accomplish the object of our invention in the manner and by the means hereinafter described in detail and claimed, reference being made to the drawings accompanying the specification, in which the same letters of reference indicate like parts in all the figures of the drawings, in which- Figure 1 is a front view of an elevator car and shaft, showing our improved device as it appears when the elevator is in working order. Fig. 2 is a central vertical section of the same, showing the cable broken and the car locked. Fig. 3 is a top plan View. Fig. 4 is aplan view on the line a: w of Fig. 1. Fig. 5 is a detail view of one of the gear-wheels.

In accomplishing the object of our invention we provide a cross-head A, which is supported normally on or by the cross-head B, permanently attached to the top of the cage or car 0. The cross-head B is provided midway of the length thereof with a slot I), through which passes for a. distance the end of a fiat rod D, to the extreme upper end of which is attached a cable E for lifting or lowering the cage or car. On each side of the cross-head B are pivotally secured thereto two tilting levers F F, provided with longitudinal slots f in each of theirlower ends which cross each other at an acute angle when in their normal positions, their upper ends being free and resting at the side of the cross-head B below the upper face thereof. Passing through each of the slots f in the arms of the tilting levers, and through an aperture in the lower end of the supporting-rod D is a pin or rod G, provided with means to retain it within the slots f. Transversely of the car, underneath the cross-head B, are secured leaf-springs H, made of highly-elastic steel or other suitable material. The ends of these springs each rest against the sides of the car just below the cross-head B and are provided with a slot midway of the length thereof, through which passes the end of the supporting-rod D. The springs H hold the rod D and the lower arms of the tilting levers F F normally depressed to a distance below the cross-head B and the upper arms of the tilting levers above the cross-head B.

The cross-head A is formed of two parallel side plates a a, secured in position at a distance from each other by cross plates or bars a, secured to their upper and lower edges in any suitable manner. Mounted on axles h h, between the plates a a, at each end are gearwheels I I, provided with cogs or teeth on their circumferences for a distance intermediate of the ends thereof. The face K of the circumference of the wheels I I on each side of the teeth or cogs is plain and rises above the toothed portion and is separated therefrom by flanges is. At the same distance from each end of the cross-head A are fulcrumed on rods K K a pair of levers L L, each one of the two pairs having a short arm Z and a long'arm l, the short arm Z and the long arm 1, respectively, being of the same length, the long arms projecting toward the middle of the cross-head and each lever of a pair resting opposite each other against the inner sides of the plates (1 a. Each pair of levers has pivotally secured in the ends of the long arm thereof the ends of the arms of depending loops M M. The middles of the loops M M are held in apertures m m in the supporting-rod D. The short arms Z of the levers L L have both ends of friction-bands N N formed of steel or any suitable material se cured to the upper edges thereof, the bands passing around the plain surfaces K K of the gear-wheels I I. The short arms Z of the levers L L are wide and the ends circular, and

the rods K K on which they are fulcrumed pass through the levers near their lower edges. Their upper edges are provided with V-shaped recesses O, inclined at their upper ends toward the long arm of the lever, and one of the ends of each of the friction-bands that pass around the gear-wheels I I is secured in the recess of the lever to which it is attached, and it next passes over the end of the lever, thence under and around the gear-wheel, and back beyond the recess it started from and is then secured to the upper edge of the lever. Vhen the long ends of the levers L L are lifted, the friction-bands are thrown out of close contact with the plain faces K K of the gear-wheels I I, and when the ends of the levers are depressed the bands are brought into binding contact with the faces K K, and further revolution of the wheels is PIQXGlltQd. Racks P P extend from the bottom to the top of the elevator-shaft on each side thereof and opposite each other. A-shaped teeth or spurs 1) project at right angles from the face of the racks P P and mesh or interlock with the teeth or cogs 2' on the gear-wheels I I in the ends of the cross-head A. Guides Q Q to prevent a sidewise or rocking movement of the car are secured to the sides of the car, and guides q q rise for a distance from the ends of the crosshead A. The racks P P project within these guides.

Then the car is supported by the cable E, it may be moved freely up and down the elevator-shaft. If the car is allowed to rest on the bottom of the shaft or on supports at any point therein and the lifting-cable E is slack, the springs II force the supporting rod D downward, carrying with it the lower ends of the tilting levers F F. This elevates the upperends of the levers F F and brings them in contact with the under side of the crosshead A, lifting it up, and by this movement drawing down the long arms of the levers L L, secured to the supporting-rod D by the loops M M, at the same time tightening the pressure of the friction-bands N N on the plain surfaces K K of the gear-wheels I I. Should the cable by which the car is raised and lowered break, or the means by which the cable is operated fail to support it, so as to prevent a falling movement of the car, an operation of the device similar to that described when the car is resting on a support will occur. The springs with the weight of the cage or car will instantly draw the friction-bands N N rigidly around the gear-wheels I I and prevent their turning, and the car will come to a standstill at any point where it may be when the breaking of the cable or the falling motion of the car takes place.

Our automatic stop may be used with equal advantage in both freight and passenger elevators, its effective action being due solely to.

a falling motion of the car or cage ora slackening of the cable which permits the instantaneous action of the spring and the locking operation that thereby ensues.

sistin g of a cross-head normally supported by the car, gear-wheels having teeth meshing with teeth in vertical racks on the sides of the elevator-shaft and journaled in the ends of said cross-head, and means forpreventingthe revolution of said gear-wheels by the weight of the descending car if the hoisting-cable breaks, substantially as shown and described.

2. An automatic stop for elevator-cars consisting of a cross-head normally supported by the car, gear-wheels journaled in the ends of said cross-head, the circumferences of said gear-wheels provided with toothed sections meshing with the teeth of vertical racks on the sides of the elevator-shaft and with plain sections, friction-bands passing around said plain sections and means for drawing said bands in braking contact with said gearwheels and preventing their revolution, by the weight of the descending elevator-car, in case the hoisting-cable breaks, substantially as shown and described.

3. An automatic stop for elevator-cars consisting of a cross-head normally supported by the car, gear-wheels journaled in the ends of said cross-head, the circumferences of said gear-wheels provided with toothed sections meshing with teeth of vertical racks on the sides of the elevator-shaft and with plain sections, friction-bands passing around said plain sections, levers fulcrumed in said crosshead and connected with said friction-bands, and means for depressing said lever and drawing said friction-bands in braking contact with said plain sections and preventing the revolution of said gear-wheels by the weight of the descending car in case said hoistingcable breaks, substantially as shown and described.

4. In automatic stops for elevator-cars, the combination with said car, of a cross-head normally supported by the car, gear-wheels journaled in the ends of said cross-head, the circumferences of said wheels provided with toothed sections meshing with the teeth of vertical racks on the sides of the elevatorshaft and with plain sections, friction-bands surrounding said plain sections, levers fulcrumed in said cross-head and connected with said friction-bands and means for drawing said levers down and bringing said bands in braking contact with said gear-wheels, substantially as shown and described.

5. An automatic stop for elevator-cars consisting of a cross-head normally supported by the car, gear-Wheels journaled in the ends of said cross-head, the circumferences of said gear-wheels provided with toothed sections meshing with teeth of vertical racks on the sides of the elevator-shaft, and plain sections, friction-bands passing around said plain sections, levers fulcrumed in said cross-head and connected with the ends of said frictionbands, loops connected to the inner ends of said levers and a supporting-rod attached at its upper end to the hoisting-cable and at its lower end to the car and means to pull said levers down drawing the friction-bands in braking contact with said gear-wheels, substantially as shown and described.

6. An automatic stop for elevator-oars consisting of a cross-head normally supported by the car, gear-wheels journaled in the ends of said cross-head, the circumferences of said wheels provided with toothed sections meshing with the teeth of vertical racks on the sides of the elevator-shaft and with plain sections, friction-bands passing around said plain sections, levers f ulcrumed in said crosshead having their outer ends attached to said friction-bands on their upper faces, loops connected with the inner ends of said levers, a supporting-rod attached at its upper end to the hoisting-cable, and two pairs of tilting levers fulcrumed to the sides of a cross-head secured to the elevator-car, and having their lower ends slotted and pivotally connected to said supporting-rod by a pin passing through said slots, substantially as shown and described.

7. An automatic stop for elevator-cars consistin g of a cross-head normally supported by the car, gear-wheels journaled in the ends of said cross -head, the circumferences of said wheels provided with toothed section's meshing with the teeth of vertical racks on the sides of the elevator-shaft and with plain sections, friction-bands passing around said plain sections, levers fulcrumed in said crosshead and attached at their outer ends on their upper faces to said friction-bands, loops connected with the inner ends of said levers, a supporting-rod connected with said loops and attached at its upper end to the hoisting-cable, two pairs of tilting levers fulcrumed to the sides of a cross-head secured to the car and having their lower ends slotted and pivotally connected with said supporting-rod by a pin passing through said slots, and springs for holding said supporting-rod normally depressed, substantially as shown and described.

In testimony whereof We hereto affix our signatures in the presence of two witnesses.

ROBERT T. WITHERS. BENJAMIN E. BLACKMAN. Witnesses:

A. MARTIN GRAHAM, H. K. GREGORY. 

